The object is to investigate pathomechanisms of chemically induced depigmentation found in occupational and industrial diseases. Both in vivo and in vitro models for chemical depigmentation will be established. These studies concern differential effects of chemical agents on skin melanocytes and aim for elucidation of skin factors which determine the differences. The study will be accomplished by use of biological, biochemical and histochemical techniques. In addition, we will try to develop a chemical and quantitative technique to screen other chemicals as potential causes of skin depigmentation.